Studying in a public place like a station or bus is the worst. And studying in a library or home is the best. studying in a bus or station is worst because there are, at most times, noisy people around. The more unnecessary noise the less focused you are. And studying at home or a library is way better. The library is quiet so you wouldn't have to worry about not concentrating; being at home may be better because the familiar surroundings keep you comfortable.
I would say that the answer is probably 3. Hope this helped!
-TTL
Affective cause that's like an influence
Antonyms for "delicate" include: sturdy, robust, strong, indestructible .
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Note: These are words that come to mind.
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